Minimum parking requirements create too much parking, reduce the supply of housing, and increase traffic congestion. Without parking requirements, the market would provide fewer parking spaces, resulting in fewer cars and more housing units. Evidence to support this argument is inconclusive, however, in part because few local governments have removed their parking requirements. Even when they do adjust parking requirements, the changes are usually quite minor, often targeting small areas (e.g., near a rail station) and including only a few development types.